Device for analysing the grain classification of a soil sample

ABSTRACT

A device for analysing the grain classification of soil samples includes sedimentation and compensation pipes, both of which are filled to a common level with liquid. A pressure difference pick up device connects the compensation pipe to the sedimentation pipe at a region above the lower end of the latter and provision is made for dumping a soil sample into the sedimentation pipe. After the sample is dumped, the levels of liquid in the two pipes are equalized either by means of an overflow pipe and stop valve connected with the sedimentation pipe or by a throttle flow connection between the two pipes.

3,788,146 [4 Jan. 29, 1974 6/1966 Great Britain........................

[ DEVICE FOR ANALYSING THE GRAIN CLASSIFICATION OF A' SOIL SAMPLE d n an w. O r B a Sr Oe S n Q S CWW m h m wm i r re mmm mm am &E Unac amm mmHS PAA k u w S e e r V m a m m m m mm mm 0e CN n O t n e V n I 1 5 7Ballast-Nedam- Groep N.V., Amsterdam, Netherlands May 9; 1972 ABSTRACT[73] Assignee: Ramik A device for analysingthe grain classification ofsoil 22 Filed:

Appl. No.: 251,829 samples includes sedimentation and compensationpipes, both of which are filled to a common level with liquid. Apressure difference pick up device connects the compensation pipe to thesedimentation pipe at a region above the lower end of the latter andprovision is made for dumping a soil sample into the sedimentation pipe.After the sample is dumped, the levels of iquid in the two pipes areequalized either by means of an overflow pipe and Stop valve connectedwith the sedimentation pipe or by a throttle flow connection between thetwo pipes. I

4/1963 FOREIGN PATENTS OR APPLICATIONS 10 Claims;

2 Drawing Figures PATENT EDJAH 29 974 rfdff/ DEVICE FOR ANALYSING THEGRAIN CLASSIFICATION OF A'SOIL SAMPLE The invention relates to a devicefor analysing the grain classification of a soil sample, comprising apressure difference pick up positioned between a sedimen-.

tation pipe and a compensation pipe, which pressure difference pick upis connected to a registrator and comprises a measuringmembraneseparating the liquid of the sedimentation pipe from the liquid of thecompensation pipe.

Such a device is known. 7

During analysing a soil sample with the known device the grainclassification is determined by measuring the fall velocity of thegrains. When the soil sample is dumped into the sedimentation pipe thelevel of the liquids in the sedimentation pipe raises in dependence onthe volume of the soil sample, so that the measured value picked up bythe pressure difference pick up is dependent from this volume. Moreoverthe measuring membrane of the pressure difference pick up is preloadedby the rise of the level.-The pressure difference pick up is lesssensitive when measuring small quantities because of this pie-load.

The invention improves the device of the above mentioned kind in thisrespect by levelling means for levelling the levels of the liquids inthe compensation .pipe and the sedimentation pipe. The rise of level inthe compensation pipe and the sedimentation pipe is therefore similar,so that the measuring membrane of the pressure difference pick up comesat both sides under the influence of an equal increase of thehydrostatic pressure.

If the registrator is carried out as an X-Y recorder, this X-Y recorderregistrates a graph independent on the volume of the soil sample andreproducing immediately the grain classification proportionally.

In order to measure the volume of a soil sample the levelling meanspreferably comprise a stop valve.

Preferably the pressure difference pick up is connected to a tactilepoint of the sedimentation pipe-situated above the lower end thereof.-Then the value picked up by the pressure difference pick up decreases independence on the grains passing by the tactile point.

The above mentioned and other features according to the invention willbe elucidated in the following descriptionwith reference to a drawing.

FIGS. 1 and 2 of the drawing each show schematically a device-accordingto the invention.

The device of FIG; 1 comprises a sedimentation pipe 1 filled with water39, a compensation pipe 2, also filled with water 39, a pressuredifference pick up 4 positioned there between and having a measuringmembrane 40-separating the water 39 of the sedimentation pipe 1 from thewater of the compensation pipe 2. The electrical signal given by themeasuring membrane 40 dependent on the deformation of the measuringmembrane 40 is connected via an amplifier 18 to the Y- input of aregistrator carried out as X-Y recorder.

The X-input 7 of the X-Y recorder 6 is connected to a voltage generator15 delivering a voltage varying logarithmically and proportionally withthe time and which voltage generator is switched on by means of a switch8.

A swivelling holder 9 for receiving the soil sample to be analysed lieson the sedimentation pipe 1. The

holder 9 is attached to a handle 14 and an operation lever 10 forclosing the switch 8. I

The sedimentation pipe 1 communicates with an overflow pipe 11, whichoverflow pipe reaches to the level 12 as well as the compensation pipe 2and which overflow pipe constitutes levelling means for levelling thelevels of the sedimentation pipe 1 and the compensation pipe 2. Theoverflow pipe 11 comprises a stop valve 13.

Analysing the soil sample 3 by means of this device takes place asfollows:

Initially the sedimentation pipe 1, the compensation pipe 2 and theoverflow pipe 11 are all filled with water to level 12, the stop valve13 is closed and the holder 9 comprises a washed and weighed soil sample3. By swivelling the holder 9 with the hand at handle 14 the soil sample3 is dumped into the sedimentation pipe 1 and the voltage generator 15is started at the same time by closing the switch 8, so that the pen 16moves now logarithmically in X-direction over the paper 17 positioned onthe X-Y recorder 6. By increase of the weight of the column in thesedimentation pipe 1 with the weight of the soil sample 3 the pressuredifference picked up by the pressure difference pick up 4 increasesinitially, which can be observed as a large Y- deflection a of pen 16.Soon after this deflection a stop valve 13 is opened and the level ofthe water 39 in the sedimentation pipe 1 sinks to level 12 by iove'rflowof water through the overflow pipe 11. .This results in a decrease ofthe Y-deflection to Y-deflection 1;. From this difference a b the totalsoil volume of the soil sample 3 can be calculated.

FIG. 2 shows a device according to the invention which inter aliadiffers in construction and operation from the device according to FIG.1 in that the levelling means of FIG. 2 are constituted by a connectingpipe 19 with a throttle 20 instead of by an overflow pipe ll so that thewater levels in thepipes land 2 come with some delay to the same level21and thepressure difference pick up 4 is discharged of a pre-tensionresulting from a level difference. During dumping the soil sample 3 intothe sedimentation pipe 1' the pressure pick up 4 picks up a pressureimpulse, which when exceeding an adjusted value, closes the switch 28via a high pass filter 30 resulting in starting of the voltage generator15, so that the X-input 7 of the X-Y recorder 6 is fed with alongitudinally and proportionally increasing voltage.

In the FIGS. 1 and 2 the pressure difference pick up 4 is under theinfluence of each grain found in the sedimentation piep 1 over itslevel. As soon as a grain passes by this level 22, the pressuredifference and with that the Y-deflection decreases. The Y-deflection isa measure forthe percentage of soil found above the level 22 said coilconsisting of grains smaller than grains passing the level 22. Thedecrease of this percentage is shown in the graph 23. For obtaining afixed maximum deflection with is independent on the volume of the samplethe initial deflection c is compared with a built-in signal 33 of apotential meter 34 corresponding with the fixed deflection d of percent.The subsequent signals are multiplied by the ratio between deflection cand the fixed deflection d. For this purpose the amplifier 18 isconnected to a store 35, the built-in relay ofwhich is excited, after aperiod of time adjusted in a retarder 36 of e.g., 2 seconds has elapsed,since the passing by of a signal through the high pass filter 30. Theconstant signal stored in the store 35 after this period of timecorresponds with 100 percent of the soil sample. During falling of thegrains the amplified signal of the pressure difference pick up 4decreases. This varying signal is multiplied in the multiplier 37 with afixed-adjusted value 33 of the potential meter 34, divided .in thedivisor 38 by the output signal of'the store 35 and supplied to theY-input 5 of the X-Y recorder 6. As the relation between the fallvelocity of the grains and their size is known, it is known for eachpoint of time during analysis which size the grains passing by the level22 have. This size of the grains is reproduced at the X-axis in p. Thegraph 23 represents the grain classiflcation of the soil sample 3.

As the pressure difference pick up at 4 at a level 22 above the lowerend is connected to the sedimentation pipe 1, it is not objectionable ifthere are under in the sedimentation pipe 1 analysed soil samples 24yet. As

a result it is not necessary to clean the sedimentation pipe 1 each timeafter analysis.

The registrator can be carried out as a digital registrator instead ofan X-Y recorder.

I claim:

l. A device for analysing the grain classification of soil samplescomprising, in combination:

a vertically disposed sedimentation pipe having a closed lower end;

a vertically disposed compensation pipe;

a pressure difference pick up device connecting said compensation pipewith said sedimentation pipe, said sedimentation pipe and saidcompensation pipe being filled with liquid to a common height which isabove said pressure difference pick up device;

measuring means connected with said pressure difference pick up devicefor measuring pressure differences sensed thereby;

means for dumping a soil sample into the liquid in said sedimentationpipe; and

levelling means for equalizing the levels of liquid in saidsedimentation and compensation pipes after a soil sample has been dumpedand during measurement by said measuring means.

2. A device according to claim 1 wherein said levelling means comprisesa flow connection between said compensation pipe and the upper regionofsaid sedimentation pipe.

3. A device according to claim 2 wherein said flow connection includes athrottle.

4. A device according to claim 1 wherein said levelling means comprisesan overflow pipe connected to said sedimentation pipe.

5. A device according to claim 4 wherein said levelling means furthercomprises a stop valve in said overflow pipe. 7

6. A device according to claim 5 wherein said pick up devicecommunicates with said sedimentation pipe at a point above said lowerend of the sedimentation pipe.

7. A device according to claim 4 wherein said pick up devicecommunicates with said sedimentation pipe at a point above said lowerend of the sedimentation pipe.

8. A device according to claim 3 wherein said pick up devicecommunicates with said sedimentation pipe at a point above said lowerend of the sedimentation pipe.

9. A device according to claim 2 wherein said pick up devicecommunicates with said .sedimentation pipe at a point above said lowerend of the sedimentation pipe.

l0. A device according to claim 1 wherein said pick up devicecommunicates with said sedimentation pipe at a point above said lowerend of the sedimentatin pipe.

1. A device for analysing the grain classification of soil samplescomprising, in combination: a vertically disposed sedimentation pipehaving a closed lower end; a vertically disposed compensation pipe; apressure difference pick up device connecting said compensation pipewith said sedimentation pipe, said sedimentation pipe and saidcompensation pipe being filled with liquid to a common height which isabove said pressure difference pick up device; measuring means connectedwith said pressure difference pick up device for measuring pressuredifferences sensed thereby; means for dumping a soil sample into theliquid in said sedimentation pipe; and levelling means for equalizingthe levels of liquid in said sedimentation and compensation pipes aftera soil sample has been dumped and during measurement by said measuringmeans.
 2. A device according to claim 1 wherein said levelling meanscomprises a flow connection between said compensation pipe and the upperregion of said sedimentation pipe.
 3. A device according to claim 2wherein said flow connection includes a throttle.
 4. A device accordingto claim 1 wherein said levelling means comprises an overflow pipeconnected to said sedimentation pipe.
 5. A device according to claim 4wherein said levelling means further comprises a stop valve in saidoverflow pipe.
 6. A device according to claim 5 wherein said pick updevice communicates with said sedimentation pipe at a point above saidlower end of the sedimentation pipe.
 7. A device according to claim 4wherein said pick up device communicates with said sedimentation pipe ata point above said lower end of the sedimentation pipe.
 8. A deviceaccording to claim 3 wherein said pick up device communicates with saidsedimentation pipe at a point above said lower end of the sedimentationpipe.
 9. A device according to claim 2 wherein said pick up devicecommunicates with said sedimentation pipe at a point above said lowerend of the sedimentation pipe.
 10. A device according to claim 1 whereinsaid pick up device communicates with said sedimentation pipe at a pointabove said lower end of the sedimentatin pipe.